1. Field of the Invention
The present invention relates to rotor blades, particularly those intended for a shrouded antitorque tail rotor (fenestron.TM.--registered trademark of the French company EUROPCOPTER) for a helicopter. It relates more specifically to the device for attaching such a blade to the hub of said rotor.
2. Description of the Related Art
It is known that antitorque tail rotor blades for helicopters are generally set by their root into the hub of said rotor, by means of two bearings which are separated from one another along the length of said root. They are also attached near the center of the hub by members which are elastically deformable in terms of torsion, which allow the angle of incidence to be varied while at the same time withstanding the centrifugal force which is exerted on the blades as they rotate.
These members which are elastically deformable in terms of torsion are either metallic (for example a bundle of superimposed leaves made of stainless steel) or made of a fiber-resin composite (it then being possible for each elastic member to be an extension of a blade, itself made of composite), depending on the design of said blades.
Whatever the design of these members which are elastically deformable in terms of torsion, these members constitute critical elements of said rotors because they experience high tensile stresses under the action of centrifugal force and, above all, because they experience high torsional fatigue loads for controlling the incidence, and so, in order to reduce the torsional stresses and extend the life of said members, these members have to be made as long as possible, although this increases the radial size of the rotor hub.